ISSN:
0021-9304
Keywords:
protein adsorption
;
grafted PEO
;
reflectivity
;
star polymers
;
end-functional polymers
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
,
Technology
Notes:
Four different poly(ethylene oxide) [PEO] molecules were compared as grafted polymer layers for biomaterials' substrates: two linear polymers and two star polymers. Conditions maximizing surface coverage for each molecule were employed with the aim of inhibiting protein adsorption and increasing the density of end groups. Neutron reflectivities of the grafted layers immersed in deuterium oxide (heavy water) were measured and used to calculate volume fraction profiles of the polymer as a function of distance from the surface. These density profiles were combined with protein adsorption data on the grafted layers to compare with recent theoretical and experimental studies of protein resistance by PEO at surfaces. We found that the grafting density is maximized by coupling the linear PEO from a K2SO4 salt buffer, which is a poor solvent for PEO. However, the grafting density of star PEO was maximized when no K2SO4 was used and the stars were dissolved near the overlap concentration. Concentration profiles obtained from the reflectivity data show that the hydrated polymers swell to ∼ 10 times the dried layer thickness and exhibit a low density (maximum volume fractions 〈 0.4 PEO) throughout the layer. The PEO surfaces obtained with both the star and linear polymers resisted adsorption of cytochrome-c and albumin except for a small amount of cytochrome-c adsorption on the short, many-armed star polymer surface. A hypothesis of adsorption on the star polymer layer is presented and criteria for controlling receptor-mediated cell-substrate interactions by ligand-modified chain ends are discussed. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 498-509, 1998.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
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